This relates generally to wireless communications.
The capacity of current cellular telephone systems is limited by co-channel interference. In the downlink, co-channel interference is due to transmissions from the base stations in neighboring cells. The strongest co-channel interference is experienced by the subscriber station near the cell edges. Thus, referring to FIG. 1, the subscriber station A is close to an edge of the cell C of base station BS1 and may receive co-channel interference from base station BS2, for example.
Multiple base station transmit cooperation (MBSC) and single base station transmit nulling (SBSN) can be exploited to reduce co-channel interference with significant gain. Both schemes involve an estimate of the channel quality between each base station and subscriber station. However, estimating the signal to interference plus noise ratio (SINR) for a weak neighboring base station may be difficult. The preambles from multiple base stations are superimposed and the preamble detection rate from a weak base station is low. In addition, feedback of SINRs for all base stations is multiplied by the number of base stations and may be prohibitive due to the cumbersome overhead. Information exchange among the local subscriber stations has been proposed to reduce feedback, but it requires additional resources allocated for the local exchange.